# usage(8)

## NAME

         usage - installing and using Minix

## DESCRIPTION

         This manual page describes the installation  and  use  of  Minix  from  a
         System  Administrators point of view.  It contains an installation guide,
         instructions on how to do the initial configuration and some other  info.
         Please  read  this  document entirely before attempting to install Minix.
         The installation  steps  are  in  the  proper  order,  but  not  all  the
         information  you  may  need  is  presented  at  the  right moment.  Other
         detailed information that may be useful  can  be  found  in  boot(8)  and
         hier(7).

      1. REQUIREMENTS
         The minimum system Minix can be installed on comfortably is an IBM  PC/AT
         or  PS/2  with a 286 processor, 2 Mb memory, a 720 kb diskette drive, and
         30 Mb free space on an AT, ESDI, or SCSI hard disk (the latter controlled
         by  an  Adaptec  1540.)   Minix  for the 386 (Minix-386 for short) can be
         installed on a machine with at least a 386sx processor and 3 Mb memory.

      2. MINIX INSTALLATION BACKGROUND
         The objective of the installation is to create a partition on  your  disk
         and  to put Minix into it.  Minix really requires two partitions however,
         so the single "primary" partition is split into two subpartitions.  The a
         subpartition  will  contain  the root file system, and the c subpartition
         will contain the /usr file system.  What MS-DOS calls "drives",  i.e  C:,
         D:,  E:,  Minix  calls "file systems".  Minix does not use drive letters,
         but requires that one file system is made a part of another  file  system
         by "mounting" one on the other.  The "root" file system is always present
         and starts with the directory "/", the root of the directory  tree.   The
         root  file  system contains a few programs in /bin, device files in /dev,
         and configuration files in /etc.  This is just enough to get  the  system
         started.   Minix  will  soon extend its directory tree by mounting a file
         system on the /usr directory.  What is henceforth known as the /usr  file
         system  contains  all  Minix programs in /usr/bin, file system sources in
         /usr/src, etc, etc.  The ROOT image contains the complete Minix root file
         system,  but  USR  contains  just a small subset of the /usr file system,
         with just enough utilities to install  Minix.   The  complete  /usr  file
         system  is  split  up into the USR.TAZ, SYS.TAZ and CMD.TAZ archives that
         are installed later to fill /usr.

         Let's suppose your first hard disk, which has device name  /dev/hd0,  has
         MS-DOS  already  present  in  the first primary partition (/dev/hd1), and
         some free space left after that.  After Minix is installed in  that  free
         space the disk will look like this:

             /dev/hd0    Whole hard disk #0
               /dev/hd1    MS-DOS C: drive
               /dev/hd2    Minix primary partition
                 /dev/hd2a   Minix root partition
                 /dev/hd2c   Minix /usr partition

         /dev/hd0 is  the  sum  of  a  partition  table,  /dev/hd1  and  /dev/hd2.
         Likewise  is  /dev/hd2  the  sum  of  a subpartition table, /dev/hd2a and
         /dev/hd2c.  Read the "DEVICES" sections for  more  information  on  Minix
         devices.

      3. INSTALLATION
         You can install Minix automatically or manually as described the sections
         below.  The end result is the same, but manual installation allows one to
         deviate from the preconfigured choices.  You may wish to read the  manual
         pages  of  the  programs used below before you start.  You may especially
         want to read boot(8) if your machine is different from what the  majority
         buys,  because  you  may  need  to set a few boot parameters to configure
         drivers.  To do this type ESC to get to the Boot Monitor prompt, set  the
         appropriate  variables,  use  save  to  store  the  settings  and menu to
         continue where you left off.

         To install the system you need two diskettes: a  bootable  root  diskette
         and  a  diskette  full  of  binaries to use as /usr.  These diskettes are
         named ROOT and USR.  These two diskettes may also be combined on a single
         high density diskette.  In that case the USR part is on the c partition.

         Insert the ROOT diskette, boot the machine and type '=' to the menu.  The
         Minix  kernel  is  loaded  and  takes  control when you see the copyright
         banner.  After loading the root diskette into the RAM disk  you  will  be
         asked to finish the name of the device to mount on /usr.  Type fd0c for a
         diskette that contains both ROOT and USR, otherwise replace ROOT  by  USR
         and type fd0.  Login as root.

      4. AUTOMATIC INSTALLATION
         Type setup to start the installation script.  First it offers to  install
         a  national keyboard map.  The names should be clear, except for us-swap,
         which swaps the CTRL and CAPS LOCK keys of a standard US  style  keyboard
         for  people who believe that the natural place of CTRL is next to A.  The
         default suggested between [ and ] is the US standard keyboard.

         The next thing to do is to make a partition, for this you are placed in a
         partition  table  editor named part.  This partition table editor is very
         easy to use (in the author's opinion), but you  will  probably  hate  it.
         You  can  move all over the place with the arrow keys, change values, and
         make a mess of your partition table real  quick.   So  if  you  get  into
         trouble,  type  'q'  to  quit,  'n' to not write the table, and RETURN to
         start over.  Use the '?' key to get help.

         With the '+' and '-' keys you can select the disk device to  install  on,
         probably  /dev/hd0,  the first hard disk.  Type 'r' to load the partition
         table of the selected disk.  Either create one new partition by modifying
         a partition marked "None", or reuse an existing partition by changing its
         type to "MINIX" (hex code 81).  The FIPS program can be used under MS-DOS
         to shrink an MS-DOS partition.  FIPS splits the DOS partition in two,  so
         one  of  the  two  can be used for Minix.  You have to be absolutely sure
         which one.  When in doubt, first use  the  FDISK  program  under  DOS  to
         delete  the extra partition, and let Minix part create a new one.  DO NOT
         use part to shrink an existing partition!  Minix needs a partition of  at
         least  20  Mb, but not larger than 128 Mb (Minix-86) or 1 Gb (Minix-386).
         The system needs 30 Mb in compiled state.

         The script then wants to know the name of the partition  you've  created,
         this  name  is  probably still visible on the screen (hd2, hd6, something
         like that.)  The new partition table is reloaded into  the  disk  driver,
         and  the  new Minix partition is carved up into two subpartitions, a 1440
         kb root and the rest for /usr.

         After  making  /usr,  it  is  immediately  put  to  use  to  replace  the
         installation /usr file system so that you can remove the USR diskette and
         insert the ROOT diskette (unless they are one and the  same).   The  root
         file system is filled with the contents of the ROOT diskette and slightly
         patched up to work on the hard disk (/etc/fstab.)

         To compute the size of the so-called "second level block cache"  you  are
         asked to specify the RAM size of your machine.  If you have plenty, i.e 4
         Mb or more then simply hit RETURN,  otherwise  enter  the  size  of  your
         system RAM in kilobytes.

         You can now skip the next section and move to "TESTING", but  it  may  be
         instructive to read it anyway.

      5. MANUAL INSTALLATION
         The instructions that follow are at a very low level and require  you  to
         be very careful.  The big advantage is that you know precisely what tools
         have been used and how everything works.  The disadvantage  is  that  you
         may easily make a mistake that either forces you to start over if you are
         lucky, or wipes out the contents of your hard disk if you are not.   Only
         if  you  really  want  to  do something different should you use a manual
         installation.  Slavishly following the steps shown below will  only  make
         you end up with the same result as an automatic installation.

         Run part to make partitions to load the system into.  The best  thing  to
         do  is  to  make one large primary partition of type "MINIX" and to carve
         this partition up into  three  subpartitions  for  root  and  /usr.   The
         assumption  is  that  you will use the second partition on the first hard
         disk, /dev/hd2, and that hd2a is the root subpartition and hd2c is  /usr.
         If  you  want  to  use  the  first  partition on the second hard disk for
         instance, then substitute hd6 and hd6[ac] for the above.  On a SCSI  disk
         it  will  be  /dev/sd2  for the second partition on the disk at target 0.
         See the section on devices below, and the manual pages of part(8), hd(4),
         and  sd(4).   Start  part  and  select  the  whole  hard disk device (the
         "multiple of 5" device) that you want to  install  Minix  onto.   In  our
         example it will be /dev/hd0.
         Use part to make a single partition in the  primary  partition  table  of
         type  "MINIX",  then hit '>' on this new partition to make a subpartition
         table.

         For the root subpartition you are advised to use 1440  kb  exactly.   You
         can  make  it larger if you want to, but it is advisable never to let the
         contents outgrow a floppy.  (The ROOT diskette is a copy of a  root  file
         system, and will be used to fill your root subpartition.)

         The second subpartition is either empty or a "scratch" partition.   Minix
         no longer uses the b subpartition for anything useful anymore, but it has
         become customary to have root on a and /usr  on  c.   (You  are  free  to
         ignore this convention, of course.)

         Use the rest of the partition for the /usr c subpartition.

         When you are done check  that  /dev/hd2a  is  active  (the  *  after  the
         partition number) so you can boot from it later.

         If your  disk  has  bad  blocks  then  don't  put  the  root  or  scratch
         subpartition  on  top  of  them.  Make sure the inode tables in the other
         partitions don't have bad blocks either.  You can put  the  subpartitions
         out  of order on the disk if that helps.  Subpartition tables, other than
         the main partition table, are not sorted by the driver.

         After making the partitions you do not have to reboot.  The  disk  driver
         reloads  the  partition  tables  on the next access if the disk is not in
         use.  (Open or mounted.)

         To be able to boot from /dev/hd2a you must place a  master  bootstrap  in
         /dev/hd2.   It  has  been placed there by part if it told you that it was
         creating a new partition table, but

              installboot -m /dev/hd2 /usr/mdec/masterboot

         will put it there for sure.

         You will start by making a file system for /usr and filling it partially.
         This  may  seem  to be out of order, but you can't insert the ROOT floppy
         right now.

              mkfs /dev/hd2c
              readall -b /dev/hd2c | sh
              mount /dev/hd2c /mnt
              cpdir -v /usr /mnt

         This will create a file system on /dev/hd2c, mount it on /mnt,  and  copy
         the  contents  of  the USR floppy onto it.  The call to readall marks bad
         blocks on the file system as unusable, you can omit this on a drive known
         to be spotless (IDE or SCSI.)
         You can now use the new /usr in place of the USR floppy:

              umount /dev/hd2c
              umount /dev/fd0     # fd0c if combined
              mount /dev/hd2c /usr

         This little dance has freed up your floppy drive, so  please  remove  the
         USR diskette and replace it by the ROOT diskette.  Make a file system for
         the root with at least 512 inodes (files), and fill it from the floppy:

              mkfs -i 512 /dev/hd2a
              mount /dev/fd0 /fd0
              mount /dev/hd2a /mnt
              cpdir -v /fd0 /mnt
              umount /dev/fd0

         Remove /mnt/etc/issue to get rid of the "use setup" message  that  greets
         you  when  you boot, and edit the file /mnt/etc/fstab to name the devices
         Minix has been installed on.  In our example it should look like this:

              root=/dev/hd2a
              usr=/dev/hd2c

         Unmount the new root:

              umount /dev/hd2a

         Make it bootable:

              installboot -d /dev/hd2a /usr/mdec/bootblock boot

         The automatic script would now  set  the  rootdev  and  ramimagedev  boot
         variables.   You  can  do  this now using the edparams command, but it is
         easier to postpone it until the testing phase.  The settings should be:

              rootdev=hd2a
              ramimagedev=hd2a

      6. TESTING
         By now a new Minix system is present on your hard disk.  Time to  see  if
         it  works.   Leave the ROOT diskette in the drive and type halt.  You are
         now going to use the power of the Boot Monitor on the  diskette  to  boot
         the  Minix  partition on the hard disk.  Use the monitor command boot hd2
         to boot the primary partition Minix has been installed in.  (It is  "hd2"
         in  our  example.)  For a SCSI disk you will have to use a 'hd' name too.
         The monitor uses the BIOS, so you will have to treat  it  as  a  "normal"
         disk at this point.

         The hard disk bootstrap is now showing the menu again.  You can type  '='
         to start Minix, but you probably want to change the boot parameters.  Hit
         ESC once more to get to the command prompt.  The command set  shows  what
         the  current parameters are.  Here is an example that shows how to make a
         menu to either start Minix or boot MS-DOS:

              minix(=,Minix) {boot}
              dos(d,MS-DOS) {boot hd1}
              save

         MS-DOS is assumed to be in the  first  partition  in  the  example  above
         (hd1).   When  finished  type menu to see if the menu looks right.  If so
         hit '=' to start Minix.

      7. ADDING PROGRAMS AND SOURCES TO /usr
         The setup command can also be used to add files from floppy sets  to  the
         system.   The USR.TAZ (programs and stuff), SYS.TAZ (system sources), and
         CMD.TAZ (commands  sources)  are  all  installed  relative  to  the  /usr
         directory, so the command to use three times is

              setup /usr

         Setup will ask for the size of data on the floppies, which is by  default
         simply  the  entire  floppy.   Don't worry if you see a few "File exists"
         errors while extracting, as some directories already exist.  You need the
         USR.TAZ  set  if  you  want  a  working Minix system, SYS.TAZ if you want
         recompile the system or study it,  and  CMD.TAZ  if  you  also  want  the
         sources  of  the  simple  commands.   On a disk space starved machine you
         could opt to do without the commands sources, as they are not  absolutely
         necessary to understand Minix.

         If your machine does not have enough memory to run setup /usr  then  type
         these commands manually:

              cd /usr
              vol /dev/fd0 | uncompress | tar xvfp -

      8. NAMES
         A standalone machine will have to be given a name.  As root type

              echo name >/etc/hostname.file

         to change the host name of your machine to name.

      9. ACTIVE ON BOOT
         You  may  want  to  make  the  Minix  partition  active  so  that  it  is
         automatically  booted.   With  DOS  fdisk or Minix part, mark the primary
         partition that contains Minix active.  Using the menu  you  made  earlier
         you  can  boot  either  Minix  or  DOS  at  a keypress.  You can even set
         timeouts.  To boot Minix automatically after 5 seconds:
              main() {trap 5000 minix; menu}

         See monitor(8) for all the details on the monitor.

         If you don't trust this then you can rig up a  diskette  that  boots  the
         Minix partition when left in the drive:

              installboot -m 2 /dev/fd0 /usr/mdec/masterboot

         The number 2 indicates the hard disk partition that must be  booted,  you
         can use the numbers 1 to 9 for hd1 to hd9.

      10. DEVICES
         A crash course on the Minix devices in /dev:   The  two  hard  disks  are
         named  hd0  and hd5.  These "multiple of five" devices address the entire
         hard disk, from  the  first  to  the  last  byte.   Each  disk  has  four
         partitions,  for  disk 0 they are hd1, hd2, hd3, and hd4.  And for disk 1
         they are named hd6, hd7, hd8, and hd9.  These partitions may contain file
         systems,  hd1  often contains the MS-DOS "C:" file system.  Minix can use
         these partitions for file systems too, but you can also partition one  of
         these  "primary  partitions"  into  four  so-called "subpartitions".  The
         subpartitions of hd1 are named hd1a, hd1b, hd1c,  and  hd1d.   The  other
         partitions  may have four subpartitions that are named in the same way by
         adding a letter from a to d.  So one disk may have four  partitions,  and
         16 subpartititions total.  SCSI disks are named in the same way, from sd0
         to sd39d for all possible devices for all eight SCSI  targets.   The  two
         floppy  disks are fd0 and fd1.  Each may have four partitions named fd0a,
         fd0b, ...  fd1d.  The command MAKEDEV knows  how  to  make  devices,  and
         DESCRIBE  can  tell  you  what an unknown device may be, or even what all
         devices in  /dev  may  be  if  called  without  arguments.   Devices  are
         described  fully  in dev(4), and in the device specific manual pages like
         fd(4) and hd(4).

      11. EDITORS
         The editors available are elvis  (a  vi  clone),  elle  (a  simple  emacs
         clone),  and the old Minix mined editor.  Of these editors only elvis can
         recover your file after a system  crash.   Only  mined  is  available  at
         installation  time.   (All you need to know about mined right now is that
         CTRL-X gets you out of it.)

      12. INSTALLING ON A SCSI DISK
         Using a disk other than a hd disk complicates things  a  bit.   The  Boot
         Monitor  uses  the  BIOS,  so it names all disks with hd names.  So it is
         boot hd1 to boot partition 1, and ramimagedev=sd2a to tell Minix its root
         partition.   If you have both a normal and a SCSI disk then the disks may
         be hd0 and hd5 to the Monitor, and hd0 and sd0 to Minix.

      13. NATIONAL KEYBOARDS
         The  directory  /usr/lib/keymaps  contains  keymap  tables  for   several
         national keyboards.  If you have a German keyboard for instance, then

              loadkeys /usr/lib/keymaps/german.map

         will load the German key translation  table  into  the  keyboard  driver.
         Copy  the  map  to  /etc/keymap once Minix is installed on the hard disk,
         because having to type a key sequence like one of these:

              loadkezs -usr-lib-kezmaps-german.map
              loqdkeys =usr=lib=key,qps=french.,qp

         on a reboot gets a bit annoying after a while.  Send corrections and  new
         keymaps  to  the  person  named  below.  (Do not send a Dutch keymap, buy
         yourself a real keyboard instead.)

## SUGGESTIONS

         Below are a few useful suggestions.  Some of the information  can  be  of
         use in other situations than described here.

      14. VIRTUAL CONSOLES
         Hold down the ALT key and press the left or right arrow key, F1,  or  F2.
         This  switches  the console between two login sessions.  (Unless you have
         an old mono adapter, because virtual consoles sit in video memory, and  a
         mono adapter only has memory for one.)

         Note that kernel messages, including function key output, only appear  on
         the  first  console.   This  may  be  confusing,  but  it keeps the other
         consoles clean.

      15. LOW ON MEMORY
         The normal installation requires that you have enough memory for a  large
         RAM disk.  You can still install Minix normally if you either have a high
         density diskette drive for a combined root+usr floppy, or  you  have  two
         floppy  drives  of  at  least 720 kb.  Before booting you have to set the
         variable rootdev to the same value as ramimagedev.  This is slower then a
         RAM disk, but saves a lot of memory.

         The automatic installation script knows how to handle this new situation.
         If you install manually then you have to use

              cpdir -vx / /mnt

         to copy the root device to disk.  When it is time to fill  /usr  and  you
         only  have  one  floppy drive then hit DEL to get out of the installation
         script and reboot as described in "TESTING".  You  can  then  finish  the
         installation manually.

      16. LOW ON MEMORY AND ONLY ONE 720 KB FLOPPY DRIVE
         If you only have one 720 kb floppy drive and your system is low on memory
         then  you  can  use the TINYROOT boot image.  This image contains a small
         kernel with only the BIOS disk driver, and a small root file system.  You
         can  use  this disk to boot your machine.  Use the normal ROOT to install
         the root file system.  Keep booting your machine with TINYROOT until  you
         have  compiled  a  small  kernel  for  your system.  Use the rootdev boot
         variable to select the hard disk root file system.  Do not  use  TINYROOT
         for anything other than booting, always use ROOT when mentioned.

      17. FLOPPY DRIVE 1 IS A HIGH DENSITY DRIVE
         If you would like to install from floppy drive 1 then you need to copy at
         least one sector from the USR image onto a diskette for drive 0.  The USR
         bootstrap has been rigged to boot the other drive.

      18. INSTALLING ON A SECOND HARD DISK
         Minix doesn't care if it is installed on the second disk of a system with
         two  disks.  The only problem is to get it booted.  You can either rig up
         a diskette to boot Minix as shown earlier, or you can use the same  trick
         on the first disk.  The command

              installboot -m 5 /dev/hd0 /usr/mdec/masterboot

         will lock the first disk into booting the second disk.   Note  that  this
         command modifies the disk outside a Minix partition, overwriting a bit of
         code that has likely been put there by DOS fdisk.  First verify that  the
         Boot  Monitor  can  boot  a  DOS partition, because then the Minix master
         bootstrap can do it too.

      19. LOTS OF MEMORY ON A 286
         You will have a hard time making Minix run out of 3  Mb  memory.   Memory
         you  can  spare  can  be used for a "second level block cache" on the RAM
         disk.  The File System uses the second level cache  to  store  copies  of
         disk blocks that are pushed out of the normal (primary) block cache.  The
         size of the primary cache is compiled into the FS server, but the size of
         the second level cache can be set with the ramsize boot variable.  Set it
         to a number between 0 and 512.  512 kilobytes is enough to keep  most  of
         the compiler cached.

      20. LOTS OF MEMORY ON A 386+
         Processes can be as big as you'd like on a 386, but in practice 4  Mb  is
         nice.  The installation script sets up a second level cache for Minix-386
         of up to 1024 kilobytes.  This is because the default file  system  cache
         is  only  80  kb.   Your  first point of call is to get rid of the poorly
         performing second level cache and to assign the memory used by it to  the
         normal  block  cache by enlarging the appropriate NR_BUFS and NR_BUF_HASH
         constants in <minix/config.h> with as much as you can spare.   (1024  for
         NR_BUFS  is  the minimum to keep cc -c cached.  2048 is then a nice value
         for NR_BUF_HASH.)  Disable the second level cache, compile a new  kernel,
         reboot and set ramsize to 0.

      21. LOTS OF DISK SPACE
         The maximum file system size is 1 Gb for Minix-386 and 128 Mb for  Minix-
         86.   (Minix-86  can  handle  larger  file  systems, but fsck can't check
         them.)  Note that a Minix file  system  can  only  contain  65535  inodes
         (files),  so  the average file should be 16 kb to completely fill it.  It
         may be better to make two smaller  file  systems.   Besides,  fsck  takes
         forever on a large file system.

## SYSTEM ADMINISTRATION

         The system has been set up with the idea that working as root  is  a  bad
         thing  to  do.   As  root  you  are in no way protected from doing stupid
         things.  So don't do development as root,  but  work  as  bin!   Only  in
         exceptional  cases  do  you  want  to become root.  Being root is fun for
         wannabe hackers; administrators know better.

         To make life easier for bin, some programs  like  su(1),  install(1)  and
         shutdown(8)  treat bin and other members of the operator group as special
         and allow them the privileges of root.  (One  is  an  operator  if  one's
         group id is zero.)  Operators should share the shadow password of root by
         having ##root in their password field.  This way they all have  one  face
         (password)  to  the  outside world, forming no greater security risk than
         root alone.

         The home directory of bin contains one important Makefile.  You  can  use
         it  to recompile all the commands and libraries of the system.  Type make
         to see the usage message.  If you want to compile just one  command  then
         you  can  simply  type  make to do so.  To put it in its proper place you
         have to type make install.  Read the Makefiles in the  commands  and  lib
         subdirectories  to understand how everything is put together.  If you are
         tight on memory then make may fail to traverse down the source  tree  and
         also  compile  things.   You will have to type make in each subdirectory.
         You can run make in /usr/src at the end to see if you've missed something
         or not.

         The login shell of bin is ash, the BSD shell.  It has  been  modified  to
         offer  simple  line editing using the editline(3) library.  Ash is rather
         big, so you may have to change bin's shell back to /bin/sh  with  chsh(1)
         if  you are low on memory.  Do not change root's shell to ash, and do not
         replace /bin/sh by ash.  It may run out of memory at the wrong moment.

         The kernel is not compiled from the  master  Makefile.   To  make  a  new
         kernel you have to step into the tools directory.  There you can run four
         different make commands:

         make This makes all the different kernel parts and combines them  in  the
              file named image.

         make fdboot
              As above and then makes a boot floppy that you can  use  to  restart
              your system with.  You are prompted for the floppy device name.

         make hdboot
              First makes the image file and then copies  it  into  the  directory
              /minix.   If there are already two images in that directory then the
              newest image will be removed to make space for this newer image.  It
              is  assumed  that  the oldest image is the most stable system image,
              one that always works, and that the newest  image  is  experimental.
              Check  beforehand  what  /minix contains before you run make hdboot.
              Remove the oldest image if you want  another  image  to  become  the
              stable  image.   The Boot Monitor chooses the newest image in /minix
              to boot.  You can use the monitor  command  ls  minix  to  view  the
              images  present,  and set the image variable to the full name of the
              image you want to use instead  if  the  newest  doesn't  work.   The
              images  in  /minix  are  named  using  the Minix release and version
              numbers with an extra  revision  number  added  to  distinguish  the
              images.

         The first new kernel you would like to make is one  configured  for  your
         system.   The  kernel  you  are  running  now  contains several hard disk
         drivers you don't need, and it does not have a TCP/IP server that you may
         want  to  have.   In <minix/config.h> you can find a number of ENABLE_XXX
         variables that can be set to 0 to exclude, or 1 to include  a  particular
         driver.   Another  driver related variable is DMA_SECTORS.  This variable
         sets the size of a buffer used by DMA based disk  drivers  (all  but  the
         floppy, AT/IDE, and Adaptec drivers).  Raise its value to greatly improve
         throughput, especially writing.  A value of 16 shows good results.   (The
         BIOS  driver  benefits  most,  because  it is a long way to the BIOS from
         protected mode, especially from 286 protected mode.)   You  can  increase
         NR_CONS  if you want to have more virtual consoles.  Having more consoles
         costs little memory, because all the consoles are kept in  video  memory.
         Scrolling  speed  of  the  console  will go down if more virtual consoles
         share the available memory.  CGA cards have space for 4 consoles, EGA and
         VGA can have 8 consoles.  The NR_PTYS variable sets the number of pseudo-
         ttys.  You need pseudo-ttys to be able to login remotely over  a  network
         with the rlogin command.  Each remote login session needs one pseudo-tty.
         If you fear that the system will now run out of processes  then  increase
         NR_PROCS.  Configuring a new kernel is sometimes not enough to enable new
         devices, you sometimes need to use the MAKEDEV command to make new device
         files  in  /dev.   For  pseudo-ttys you also have to check if /etc/ttytab
         mentiones the new devices.

         New additions to the system can be made in the /usr/local tree.  An empty
         directory  tree has been set up for you and binaries and manual pages are
         already in the search paths.  You can make a  new  user  entry  with  the
         adduser command.

         The TZ variable in /etc/profile tells the time zone offset from the  wall
         clock  time  to  GMT.   You  have  to change it for your time zone.  (See
         TZ(5).)

         The function keys produce debug dumps, showing various  interesting  data
         about  the system.  F1 lists processes and F5 shows ethernet stats, which
         may be of use now.  Read console(4) to know all the details of the screen
         and keyboard.

      22. SYSTEM SHUTDOWN
         You can't just turn a Minix system off.  Minix must be told to flush  the
         modified   data   in   the   file  system  cache  first.   The  following
         commands/keystrokes can be used to exit Minix properly:

         shutdown
              First alert all users  and  then  all  processes  of  the  impending
              shutdown then halt or reboot the system in one of various ways.  See
              shutdown(8).

         reboot / halt
              Alert all processes of the system shutdown then reboot or halt.

         CTRL-ALT-DEL
              Halt the system by running shutdown -h now.

         Minix  halts  by  returning  to  the  Boot  Monitor,  Minix  reboots   by
         instructing  the monitor to reboot Minix.  (Minix is just a subprocess to
         the monitor.)  Either halt Minix  and  use  monitor  commands  to  escape
         Minix, or use shutdown -R to reset the system.

## FILES

         /usr/ast    Honorary home directory of Andew S.  Tanenbaum.   Doubles  as
                     the place where the default setup for a new user is found.

## SEE ALSO

         monitor(8), boot(8), part(8), mkfs(1), mount(8), M(8), fstab(5), hier(7),
         console(4), dev(4), adduser(8), TZ(5), mkdist(8), shutdown(8).
         "Operating Systems - Design and Implementation" by Andrew S. Tanenbaum.

## NOTES

         The  notation  <file.h>  refers  to  a  C  language   include   file   in
         /usr/include.

         Root and bin do not have the current directory in  their  program  search
         path  to  avoid executing programs left around by malicious people.  This
         means that to run foo from the current directory, ./foo must be typed.

         Some of the commands have changed  since  earlier  Minix  versions.   For
         instance mkfs doesn't need a size argument anymore, and vol automagically
         determines if it needs to read or write.  Keep this in mind if you use an
         older Minix version to examine the newer system.

## BUGS

         There are many PS/2 models, all different.  Some  will  run  Minix,  some
         won't,  some  crippled  if  you  lie to Minix by setting processor to 86.
         Almost no PS/2 has a standard disk, so setting hd to esdi or bios will be
         necessary.

         While testing a full library rebuild of this  distribution  it  sometimes
         happened that some things were not put back into the library.  This seems
         to be fixed, but we do not understand why the fix fixed the problem.   So
         if  you  see  strange "undefined" errors when compiling a program after a
         library rebuild then run make install again in /usr/src/lib/ to  try  and
         add the missing pieces.

         Except for the floppy driver none of the DMA based drivers know about DMA
         being  limited  to  a  24  bits  address, i.e. the first 16 Mb.  So under
         Minix-386 you run a slight risk that a tar or dd command may use a buffer
         above  16  Mb  for  reading  or writing to a character device.  This only
         happens if the low 16 Mb is taken by some huge processes,  and  you  have
         more than 16 Mb, of course.

## AUTHOR

         Kees J. Bot (kjb@cs.vu.nl)